<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div class="box">盒子1</div>
    <div class="box">盒子2</div>
    <div id="nav">
        <ul>
            <li>首页</li>
            <li>产品</li>
        </ul>

    </div>

    <script>
        //1.getElementsByClassName根据类名获得某些元素集合
        var boxs = document.getElementsByClassName('box');
        console.log(boxs);

        //2.万能选择器 querySelector 返回指定选择器第一个元素对象,切记里面的选择器需要加符号
        var firstBox = document.querySelector('.box')  //表示类选择器
        console.log(firstBox);

        //
        var nav = document.querySelector('#nav')  //表示id选择器
        console.log(nav);

        var li = document.querySelector('li')  //标签选择器不需要写
        console.log(li);


        //3.万能所有的选择的选择器querySelectorAll()返回指定选择器所有元素对象的集合
        var allBox = document.querySelectorAll('.box');
        console.log(allBox);

        var lis = document.querySelectorAll('li');
        console.log(lis);
    </script>




</body>

</html>